Pitfalls in Fine Needle Aspiration Cytology of Extraadrenal Paraganglioma: A Report of 2 Cases

BACKGROUND: Fine needle aspiration (FNA) is commonly used as an initial diagnostic tool in the evaluation of mass lesions. However, extraadrenal paragangliomas (EAPs) are not commonly seen on FNA and, when encountered, can pose a diagnostic challenge since they have a wide variety of morphologic patterns. CASES: Two intraabdominal EAPs were misdiagnosed as an anaplastic adenocarcinoma of the pancreas with giant cell features and papillary adenocarcinoma of the pancreas. The sources of the pitfalls were inaccurate radiologic localization, misinterpretation of vascular-rich tissue fragments as papillary structures, presence of acinarmicroglandular structures, marked cellular pleomorphism (including multinucleation), prominent nucleoli and some cells with "squamoid" cytoplasm. CONCLUSION: The cytologic features of EAP, although suggestive, are not specific. A high index of suspicion and knowledge of clinical information, exact anatomic location and cytologic morphology combined with appropriate ancillary studies are the key to an accurate diagnosis.